ToneTester is a Macintosh application that tests hearing. Specifically, it looks for offsets in how each of a person's ears hears pitch (the formal term for this is "binaural diplacusis" or "interaural pitch difference"). To use it, you adjust a slider until your ears hear the same pitch, and then ToneTester tells you the actual pitch difference.. Suitable Systems. Daniel Griscom's web site, with information on his consulting business and...